In the case of the thread you're quoting, for me it's because they haven't done anything more than exchange pleasantries in passing. So the idea that he's done something to offend her, taken along with the rest of his speech about how she needs to get to know him so she won't be shy around him just sounds like a come on. It's not so much that the phrase "Have I offended you?" in and of itself is accusatory. It's how it was used in that particular situation and in conjunction with the rest of the dialog.

In your examples, reflection5, there seems to be a real reason why one person is asking if they've offended the other. There seems to be some actual behavior which is indicating that offense may have been taken in previous interaction.

But based on the OP in the other thread, there doesn't actually seem to be much basis for the question, plus (and I know I keep coming back to this) taken with the rest of the statement about her supposed shyness, yes, it's accusatory.

"Have I offended you" translates to "You're making me feel like I've offended you." At least that's how I hear it. When someone asks me if they've done something to make me mad, I usually feel like I need to apologize for acting in a way that would give that impression.

"What the eHell is your problem, mister? Have I OFFENDED you in some way? Is that glare you gave me because my body mass is just too much to be seen out in public all at once? I'm sorry, was I supposed to ask your permission before I wore this outfit? Then why the eHell were you giving me that look and making those sarcastic comments to your buddies?"

In that kind of context (which is NOT what the original thread was about!), the "have I offended you" is just a sarcastic way of accusing the other person of not observing the correct social niceties - but with a strong insinuation that the problem is on their end and that you don't really expect an affirmative answer.

"Have I offended you" translates to "You're making me feel like I've offended you." At least that's how I hear it. When someone asks me if they've done something to make me mad, I usually feel like I need to apologize for acting in a way that would give that impression.

POD. For the record, I'm the OP of the thread whose neighbor asked me if he had offended me. I had no time to establish enough of a relationship with him for him to notice if I suddenly cooled off, like this OP's coworker example.

It would've been less off putting if he had brought it up during the course of our normal interactions, for example if we had bumped into each other getting mail and he asked "You don't seem very talkative. Have I offended you in some way?" as opposed to (seemingly) randomly ringing my doorbell.

When I was younger and first in the workplace, I used to assume any time someone was acting unusually toward me, it meant they were upset with me. If it went on for a couple days, I would try to clear the air with the "Have I done something to offend/upset you?" question. Then, one day an older guy I worked with gave me some very valuable advice that I remember to this day. He told me "Don't go through life internalizing everything. It's not always about you - in fact the majority of the time, if someone is quiet, distracted etc, it's because something is going on in their life that has nothing to do with you. " He did not say any of this unkindly or in a mean way, just matter of fact and kind of reassuring. It was like a lightbulb going off. "It's not all about me - people have things going on in their lives I know nothing about."

From that point onward, if someone was acting cool or distracted, I might at most ask "Is everything ok?", but usually I just keep acting normally and eventually they resumed acting normally as well. I figure if I HAD done something to upset them, they should tell me, and if they choose not to, that was their issue.